What surface structures facilitate adhesion among oral bacteria and influence coaggregation?

• A. Capsules and exopolysaccharides mediate adhesion and coaggregation.
• B. Fimbriae and various adhesins on bacterial surfaces mediate adhesion and coaggregation.
• C. Flagella-driven motility is the primary driver of coaggregation.
• D. Endospores prevent adhesion.

Answer: (B)

Specific surface structures on bacteria mediate adhesion and coaggregation in the oral biofilm. Fimbriae (pili) extend from the cell and act as binding fibers, enabling close contact between cells, while adhesins—proteins on the fimbriae or outer membrane—recognize complementary receptors on neighboring bacteria. Together, these components drive the specific interbacterial associations that shape multispecies communities and influence how organisms cluster in dental plaque. Endospores are dormant and do not promote adhesion, and while flagella aid movement toward surfaces, they are not the primary determinants of stable interbacterial binding. Capsules and exopolysaccharides can contribute to attachment and the biofilm matrix, but the precise, receptor-mediated interactions that enable coaggregation are best explained by fimbriae and adhesins.